A top U.S. military official says the U.S. mission against a violent central African rebel group is likely to last for months, but that it has no specific timetable.

President Barack Obama announced this month that he was sending 100 military personnel to help central African governments fight the rebel Lord's Resistance Army.

Defense and State Department officials defended the program Tuesday before members of the House of Representatives Foreign Affairs Committee.

The assistant secretary of defense for international security affairs, Alexander Vershbow, said the operation is limited to helping regional governments collect and use intelligence more effectively against the LRA. He also said the Obama administration will review the effectiveness of the operation in several months.

Some lawmakers at the hearing expressed concern that the mission might grow in size, length and cost.

A top State Department official on African affairs, Donald Yamamoto, told VOA that the long-term goal is peace and stability in central Africa.

He said the U.S. took on the mission at the request of multiple central African states. The LRA has been active most recently in the Democratic Republic of Congo, South Sudan and the Central African Republic.

The LRA, once based in Uganda, is accused of attacking villages across central Africa over the past few years, killing and kidnapping hundreds of people.

The group is notorious for kidnapping people for use as soldiers or sex slaves. Three of the group's leaders, including top leader Joseph Kony, are wanted by the International Criminal Court for alleged war crimes and crimes against humanity.